The present invention relates to a novel purine compound having an adenosine receptor antagonism and to a preventive or therapeutic agent for diabetes mellitus and diabetic complications comprising an adenosine receptor antagonist having a hypoglycemic action and a glucose tolerance improving action on the basis of an inhibiting action to saccharogenesis and a promoting action to saccharide utilization at the periphery. More particularly, it relates to a preventive or therapeutic agent for diabetes mellitus and diabetic complications in which an adenosine receptor antagonist is an adenosine A2 receptor antagonist.
With regard to therapeutic agents for diabetes mellitus, various biguanide compounds and sulfonylurea compounds have been used. However, the biguanide compounds induce a lactic acidosis and, therefore, their use is limited while the sulfonylurea compounds often result in a severe hypoglycemia due to their strong hypoglycemic action and, therefore, their use is to be careful.
An object of the present invention is to provide a preventive or therapeutic agent for diabetes mellitus and diabetic complications on the basis of a new action mechanism which is different from that of conventional biguanide compounds and sulfonylurea compounds having several limitations in actual use.
The present inventors have carried out various investigations and, as a result, they have found that antagonists to adenosine receptors can be preventive or therapeutic agents of a new type for diabetes mellitus. Thus, hyperglycemia of spontaneous diabetic mice was relieved by an adenosine receptor antagonist. Such an action is presumed to be the results of inhibition of the gluconeogenic action and the glycogenolytic action, promoted by endogenous adenosine, from liver by an antagonist. Based upon such a finding, the present inventors have carried out an investigation for the compounds having excellent hypoglycemic action and glucose tolerance improving action as a preventive or therapeutic agent and have found novel purine compounds represented by the following formula (I). As a result of further investigation of their action mechanism in detail, they have found that, among the adenosine receptor antagonistic action, the adenosine A2 receptor antagonistic action is the real substance for showing the hypoglycemic and glucose tolerance improving action and have accomplished the present invention where adenosine A2 receptor antagonist is a preventive or therapeutic agent of a new type for diabetes and diabetic complications.
The novel purine compound according to the present invention is represented by the following formula (I).
A purine compound represented by the formula (I), its pharmacologically acceptable salt or hydrates thereof. 
In the formula R1 means:
1) formula: 
xe2x80x83(in the formula, X represents hydrogen atom, hydroxyl group, an optionally substituted lower alkyl group, an optionally substituted lower alkoxy group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted acyl group, an optionally substituted acyloxy group or an optionally substituted amino group; and R5 and R6 are the same as or different from each other and each represents hydrogen atom, an optionally substituted lower alkyl group, an optionally substituted saturated or unsaturated C3-8 cycloalkyl group, an optionally substituted C3-8 cycloalkyl-C2-6 alkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally protected carboxyl group or an optionally substituted four to six membered ring having at least one hetero atom. Alternatively, R5 and R6 may represent an oxygen atom or a sulfur atom together or may represent a ring being formed together with the carbon atom to which they are bonded which may have a hetero atom. This ring may be substituted.); or
2) a five- or six-membered aromatic ring which may have substituent group and hetero atom.
W represents a formula xe2x80x94CH2CH2xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94 or xe2x80x94Cxe2x89xa1Cxe2x80x94.
R2 represents hydrogen atom, an optionally substituted lower alkyl group, hydroxyl group or a formula xe2x80x94NR7R8 (in which R7 and R8 are the same as or different from each other and each represents hydrogen atom, hydroxyl group, an optionally substituted lower alkyl group, an optionally substituted acyl group, an optionally substituted C3-8 cycloalkyl group, an optionally substituted aryl group or an optionally substituted heteroaryl group. Alternatively, R7 and R8 may be a saturated ring which is formed together with a nitrogen atom to which they are bonded. This ring may further have a hetero atom or a substituent.).
R3 represents hydrogen atom, an optionally substituted C3-8 cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group or an optionally substituted C2-6 alkenyl group.
R4 represents hydrogen atom, an optionally substituted lower alkyl group, an optionally substituted C3-8 cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted C2-6 alkenyl group, an optionally substituted C2-6 alkynyl group or an optionally substituted cyclic ether.
However, the case where (1) W is xe2x80x94CH2CH2xe2x80x94 and X is hydrogen atom and an alkyl group or where (2) W is xe2x80x94Cxe2x89xa1Cxe2x80x94, R3 is hydrogen atom and R4 is an optionally substituted cyclic ether is excluded.
There has been no report that an adenosine A2 receptor antagonist is effective for prevention and therapy of diabetes mellitus and diabetic complications.
The present invention provides a preventive or therapeutic agent for diabetes, a preventive or therapeutic agent for diabetic complications, a hypoglycemic agent, an improving agent for impaired glucose tolerance, a potentiating agent for insulin sensitivity or obesity which comprises a purine compound of the formula (I), its pharmacologically acceptable salt or hydrates thereof as an active ingredient.
The present invention provides a method or a use by administrating a pharmacologically or clinically effective amount of a purine compound of the formula (I), its pharmacologically acceptable salt or hydrates thereof to a patient for prevention or therapy of diabetes mellitus, for prevention or therapy of diabetic complications, for prevention or therapy of a disease against which a purine compound of the formula (I), its pharmacologically acceptable salt or hydrates thereof is effective for its prevention or therapy, for hypoglycemia, for improvement of impaired glucose tolerance, for potentiation of insulin sensitivity, or for prevention and therapy of obesity.
The present invention provides a pharmaceutical composition containing a pharmacologically or clinically effective amount of a purine compound of the formula (I), its pharmacologically acceptable salt or hydrates thereof.
Adenosine is a nucleoside widely existing in living body and has a physiological action to a cardiovascular system, a central nervous system, a respiratory system, kidney, an immune system, etc. The action of adenosine is achieved via at least four receptorsxe2x80x94A1, A2a, A2b and A3xe2x80x94in which G protein is participated (Fredholm, B. B. et al., Pharmacol. Rev., 46, 143-156, 1994.). In 1979, adenosine receptor was at first classified into A1 and A2 on the basis of their pharmacological action and participation in adenylate cyclase (Van Calker, D. et al., J. Neurochem., 33, 999-1003, 1979.). Then A2 receptor has classified into the subtypes of A2a and A2b on the basis of high and low affinity to adenosine and to adenosine A2 agonists, i.e. NECA and CGS-21680 (Burns, R. F. et al., Mol. Pharmacol., 29, 331-346, 1986.; Wan, W. et al., J. Neurochem., 55, 1763-1771, 1990.). Although gradually, physiological and pathological significance of those receptors has been clarified in a central nervous system, a circulatory system, etc.
With regard to saccharometabolism, the following reports have been available. In an experiment using skeletal muscles, adenosine lowers the insulin sensitivity due to an agonistic action to the A1 receptor suppressing the incorporation of saccharide while an A1 receptor antagonist increases the insulin sensitivity (Challis, R. A., Biochem. J., 221, 915-917, 1984.; Challis, R. A., Eur. J. Pharmacol., 226, 121-128, 1992.). In fat cells, adenosine enhances the sensitivity of insulin via an A1 receptor, whereby incorporation of saccharide is promoted (Vannucci, S. J., et al., Biochem. J., 228, 325-330, 1992.). Further, WO 95/18128 and WO 98/03507 disclose a therapeutic agent for diabetes mellitus comprising an A1 receptor antagonist. Thus, there have been many reports concerning an A1 receptor. With regard to an adenosine A2 receptor, there is a simple description in WO 97/01551 suggesting a therapeutic agent for diabetes mellitus comprising the A2a receptor antagonist although any ground therefor is not mentioned at all. In Collis, M. G. et al., Trends Pharmacol. Sci., 14, 360-366, 1993., participation of the adenosine A2 receptor in the promotion of gluconeogenesis in hepatic cells is suggested but there is no specific description at all. On the contrary, WO 98/01459 describes a therapeutic agent for diabetes mellitus comprising the A2 receptor agonist but there is no description for the adenosine A2 receptor antagonist at all. As such, the positioning of the adenosine A2 receptor antagonist as a therapeutic agent for diabetes mellitus has been in a chaotic state.
The adenosine A2 receptor antagonist of the present invention as a preventive or therapeutic agent for diabetes mellitus and for diabetic complications is selected, for example, from the following compounds 1) to 4).
1) Formula (I) 
In the formula, R1 represents:
(1) formula: 
xe2x80x83(in the formula, X is hydrogen atom, hydroxyl group, an optionally substituted lower alkyl group, an optionally substituted lower alkoxy group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted acyl group, an optionally substituted acyloxy group or an optionally substituted amino group; and R5 and R6 are the same as or different from each other and each represents hydrogen atom, an optionally substituted lower alkyl group, an optionally substituted saturated or unsaturated C3-8 cycloalkyl group, an optionally substituted C3-8 cycloalkyl-C2-6 alkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally protected carboxyl group or an optionally substituted four- to six-membered ring having at least one hetero atom. Alternatively, R5 and R6 represents an oxygen atom or a sulfur atom together or represents a ring which may have hetero atom being formed together with the carbon atom to which they are bonded. This ring may be substituted.); or
(2) a five- or six-membered aromatic ring which may have substituent group and hetero atom.
W represents formula xe2x80x94CH2CH2xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, or xe2x80x94Cxe2x89xa1Cxe2x80x94.
R2 represents hydrogen atom, an optionally substituted lower alkyl group, hydroxyl group or a formula xe2x80x94NR7R8 (in which R7 and R8 are the same as or different from each other and each represents hydrogen atom, a hydroxyl group, an optionally substituted lower alkyl group, an optionally substituted acyl group, an optionally substituted C3-8 cycloalkyl group, an optionally substituted aryl group or an optionally substituted heteroaryl group. Alternatively, R7 and R8 represents a saturated ring which is formed together with a nitrogen atom to which they are bonded. This ring may further have hetero atom or substituent.)
R3 represents hydrogen atom, an optionally substituted C3-8 cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group or an optionally substituted C2-6 alkenyl group.
R4 represents hydrogen atom, an optionally substituted lower alkyl group, an optionally substituted C3-8 cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted C2-6 alkenyl group, an optionally substituted C2-6 alkynyl group or an optionally substituted cyclic ether group.
However, the case where (1) W is xe2x80x94CH2CH2xe2x80x94 and X is hydrogen atom and an alkyl group or where (2) W is xe2x80x94Cxe2x89xa1Cxe2x80x94, R3 is hydrogen atom and R4 is an optionally substituted cyclic ether is excluded.
That is, the present invention is the purine compound of the above formula (I), its pharmacologically acceptable salt or hydrates thereof.
Among those compounds, the preferred examples are those where W is ethynylene group or ethenylene group and the more preferred example is that where W is ethynylene group.
The purine compound of the present invention includes an ethynylenepurine compound represented by the formula (Ixe2x80x2): 
except the case where R3 is hydrogen atom and R4 is an optionally substituted cyclic ether.
2) A compound represented by the formula (VII): 
(in the formula, R1a and R2a are the same as or different from each other and each represents a C1-4 lower alkyl group or allyl group; R3a represents hydrogen atom or a C1-3 lower alkyl group; and R4a, R5a, R6a and R7a are the same as or different from each other and each represents hydrogen atom, a halogen atom, a C1-3 lower alkyl group, a C1-3 lower alkoxy group, nitro group, amino group or hydroxyl group) or a pharmacologically acceptable salt thereof.
Among those compounds, the preferred examples are those where R1a, R2a and R3a are the same as or different from each other and each represents a C1-3 lower alkyl group and any of R4a, R5a, R6a and R7a is a C1-3 lower alkoxy group, and the more preferred examples are those where R1a, R2a and R3a are the same as or different from each other and each represents a C1-3 lower alkyl group and R5a and R6a are methoxy groups.
3) A compound represented by the formula (VIII): 
(in the formula, E represents an oxygen atom, a sulfur atom, SO2 or NH; F represents a C5-6 cycloalkyl group, a pyridyl group, a thiazolyl group, a C1-6 alkyl group, an optionally substituted phenyl group, an optionally substituted phenyl-C1-2 alkyl group, a morphoinoethyl group, a furylmethyl group or a pyridylmethyl group; and G represents a furyl group, a thienyl group or an isoxazolyl group) or a pharmacologically acceptable salt thereof.
Among those compounds, the preferred examples are those where E is NH, F is 2-(4-hydroxyphenyl)ethyl group or 2-(morpholino)ethyl group and G is a furyl group.
4) A compound represented by the formula (IX): 
(in the formula, the ring M represents pyrazole or triazole; and P represents a phenyl-(C1-2)alkyl group optionally substituted with halogen atom, an alkyl group, an alkoxy group or cyano, or a C1-6 alkyl group) or a pharmacologically acceptable salt thereof.
Among those compounds, the preferred example is that where the ring M is pyrazole and P is a phenethyl group.
5) A compound represented by the formula (X): 
(in the formula, U represents an oxygen atom, a sulfur atom or NH group; V represents an optionally hydroxyl-substituted lower alkyl group, a phenyl or aralkyl group which may be substituted with a lower alkoxy group, a lower alkyl group, a halogen atom, hydroxyl group, etc. or a heteroaryl group; Z1 represents hydrogen atom, a halogen atom or a lower alkyl group; and Z2 represents a heteroaryl group such as a furyl group) or a pharmacologically acceptable salt thereof.
Among those compounds, the preferred one is that where U is an oxygen atom, V is 2,6-dimethoxyphenyl group, Z1 is hydrogen atom and Z2 is a furyl group.
The present invention provides a preventive or therapeutic agent for diabetes, a preventive or therapeutic agent for diabetic complications, a hypoglycemic agent, an improving agent for impaired glucose tolerance, a potentiating agent for insulin sensitivity or obesity which comprises an adenosine A2 receptor antagonist, its pharmacologically acceptable salt or hydrates thereof as an active ingredient.
It is preferred that the above adenosine A2 receptor antagonist is adenosine A2a and/or A2b receptor antagonist.
Examples of those which are preferred as the adenosine A2a or A2b receptor antagonist of the present invention are those where the Ki value showing an affinity to the A2a receptor by the experimental method which will be mentioned later is not more than 0.5 xcexcM, those where the IC50 value showing the suppression of cAMP production stimulated by NECA in the A2b receptor is not more than 0.7 xcexcM or those satisfying both of them. Examples of those which are more preferred are those where the Ki value showing an affinity to the A2a receptor by the experimental method which will be mentioned later is not more than 0.1 xcexcM, those where the IC50 value showing the suppression of cAMP production stimulated by NECA in the A2b receptor is not more than 0.5 xcexcM or those satisfying both of them.
The present invention provides a method or a use by administrating a pharmacologically or clinically effective amount of an adenosine A2 receptor antagonist, its pharmacologically acceptable salt or hydrates thereof to a patient for prevention or therapy of diabetes mellitus, for prevention or therapy of diabetic complications, for prevention or therapy of a disease against which an adenosine A2 receptor antagonist, its pharmacologically acceptable salt or hydrates thereof is effective for its prevention or therapy, for hypoglycemia, for improvement of impaired glucose tolerance, for potentiation of insulin sensitivity, or for prevention and therapy of obesity.
The present invention provides a pharmaceutical composition containing a pharmacologically or clinically effective amount of an adenosine A2 receptor antagonist, its pharmacologically acceptable salt or hydrates thereof.
In the formula (I), the term xe2x80x9coptionally substitutedxe2x80x9d used in an optionally substituted lower alkyl group, an optionally substituted lower alkoxy group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, etc. in the definitions for X, R2, R3, R4, R5, R6, R7 and R8 represents that each of the groups may be substituted with a group selected, for example, from a hydroxyl group; a thiol group; a nitro group; a cyano group; a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom; a lower alkyl group such as methyl, ethyl, n-propyl and isopropyl; a lower alkoxy group such as methoxy, ethoxy, n-propoxy, isopropoxy and butoxy groups; a halogenated alkyl group such as a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group and a 2,2,2-trifluoroethyl group; an alkylthio group such as a methylthio group, an ethylthio group and an isopropylthio group; an acyl group such as an acetyl group, a propionyl group and a benzoyl group; a hydroxyalkyl group such as a hydroxymethyl group, a hydroxyethyl group and a hydroxypropyl group; an amino group; a monoalkylamino group such as a methylamino group, an ethylamino group and an isopropylamino group; a dialkylamino group such as a dimethylamino group and a diethylamino group; a cyclic amino group such as an aziridinyl group, an azetidinyl group, a pyrrolidinyl group, a piperidinyl group, a perhydroazepinyl group and a piperazinyl group; a carboxyl group; an alkoxycarbonyl group such as a methoxycarbonyl group, an ethoxycarbonyl group and a propylcarbonyl group; a carbamoyl group; an alkylcarbamoyl group such as a methylcarbamoyl group and a dimethylcarbamoyl group; an acylamino group such as an acetylamino group and a benzoylamino group; an unsubstituted or C1-4 alkyl-substituted sulfamoyl group or an alkylsulfonyl group such as a methylsulfonyl group and an ethylsulfonyl group; an unsubstituted or substituted arylsulfonyl group such as a benzenesulfonyl group and a p-toluenesulfonyl group; an unsubstituted or substituted aryl group such as a phenyl group, a tolyl group and an anisolyl group; an unsubstituted or substituted heteroaryl group such as a pyrrole group, a pyrazolyl group, an imidazolyl group, a triazolyl group, a tetrazolyl group, a thiazolyl group, a pyridyl group, a pyrimidyl group and a pyrazinyl group; a carboxyalkyl group; an alkyloxycarbonylalkyl group such as a methoxycarbonylmethyl group, an ethoxycarbonylmethyl group and a methoxycarbonylethyl group; a carboxyalkoxy group such as a carboxymethoxy group; an arylalkyl group such as a benzyl group and a 4-chlorobenzyl group; a heteroarylalkyl group such as a pyridylmethyl group and a pyridylethyl group; an alkylenedioxy group such as a methylenedioxy group and an ethylenedioxy group; etc.
The halogen atom in the definitions for A and B is fluorine, chlorine, bromine or iodine.
The lower alkyl group in the definitions for X, R2, R4, R5, R6, R7 and R8 means a linear or branched alkyl group having 1-6 carbon atoms. Its examples are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, 1,2-dimethylpropyl group, 1,1-dimethylpropyl group, 2,2-dimethylpropyl group, 2-ethylpropyl group, n-hexyl group, 1,2-dimethylbutyl group, 2,3-dimethylbutyl group, 1,3-dimethylbutyl group, 1-ethyl-2-methylpropyl group and 1-methyl-2-ethylpropyl group.
The lower alkoxy group in the definitions for X means a linear or branched alkoxy group having 1-6 carbon atoms. Its examples are methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, n-pentyloxy group, 1,2-dimethylpropyloxy group, 1,1-dimethylpropyloxy group, 2,2-dimethylpropyloxy group, 2-ethylpropyloxy group, n-hexyloxy group, 1,2-dimethylbutyloxy group, 2,3-dimethylbutyloxy group, 1,3-dimethylbutyloxy group, 1-ethyl-2-methylpropyloxy group and 1-methyl-2-ethylpropyloxy group.
The cycloalkyl group in the definitions for X, R3, R4, R5, R6, R7 and R8 means a cycloalkyl group having 3-8 carbons such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group or cyclooctyl group.
The cycloalkylalkyl group in the definitions for X, R3, R4, R5, R6, R7 and R8 means a group where the above cycloalkyl group is bonded to any of the carbon atoms in the above lower alkyl group.
The lower alkenyl group in the definitions for R3 and R4 means a linear or branched alkenyl group having 2-6 carbon atoms such as vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 2-methyl-1-propenyl group, 3-methyl-1-propenyl group, 2-methyl-2-propenyl group, 3-methyl-2-propenyl group, 1-butenyl group, 2-butenyl group and 3-buteny group.
The lower alkynyl group in the definition for R4 represents a linear or branched alkynyl group having 2-6 carbon atoms such as ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 3-methyl-1-propynyl group and 2-methyl-3-propynyl group.
The acyl group in the definitions for X and R2 represents a group derived from an aliphatic saturated monocarboxylic acid such as acetyl group, propionyl group, butyryl group, valeryl group, isovaleryl group and pivaloyl group; a group derived from an aliphatic unsaturated carboxylic acid such as acryloyl group, propioloyl group, methacryloyl group, crotonoyl group and isocrotonoyl group; a group derived from a carbocyclic carboxylic acid such as benzoyl group, naphthoyl group, toluoyl group, hydroatropoyl group, atropoyl group and cinnamoyl group; a group derived from a heterocyclic carboxylic acid such as furoyl group, thenoyl group, nicotinoyl group and isonicotinoyl group; a group derived from a hydroxycarboxylic acid or an alkoxycarboxylic acid such as glycoloyl group, lactoyl group, glyceroyl group, tropoyl group, benzyloyl group, salicyloyl group, anisoyl group, vanilloyl group, piperoniloyl group and galloyl group; a group derived from various kinds of amino acids; etc.
The aryl group in the optionally substituted aryl group in the definitions for X, R3, R4, R5, R6, R7 and R8 represents phenyl group, 1-naphthyl group, 2-naphthyl group, anthracenyl group, etc.
The optionally substituted heteroaryl group in the definitions for X, R3, R4, R5, R6, R7 and R8 represents a group derived from a monocycle or a condensed ring containing 1-4 of at least one selected from the group consisting of sulfur atom, oxygen atom and nitrogen atom. Its examples are pyrrolyl group, thienyl group, furyl group, thiazolyl group, oxazolyl group, isothiazolyl group, isoxazolyl group, imidazolyl group, pyrazolyl group, thiadiazolyl group, oxadiazolyl group, triazolyl group, tetrazolyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, indolyl group, isoindolyl group, benzothienyl group, benzofuranyl group, isobenzofuranyl group, benzimidazolyl group, indazolyl group, benzotriazolyl group, benzothiazolyl group, benzoxazolyl group, quinolyl group, isoquinolyl group, cinnolinyl group, phthalazyl group, quinoxalyl group, naphthyridinyl group, quinazolinyl group and imidazopyridinyl group.
The protective group in the optionally protected carboxyl group in the definitions for R5 and R6 is, for example, a lower alkyl group such as methyl group, ethyl group and tert-butyl group; a lower alkyl group substituted with an optionally substituted phenyl group such as p-methoxybenzyl, p-nitrobenzyl, 3,4-dimethoxybenzyl, diphenylmethyl, trityl and phenethyl groups; a halogenated lower alkyl group such as 2,2,2-trichloroethyl and 2-iodoethyl; a lower alkanoyloxy lower alkyl group such as pivaloyloxymethyl, acetoxymethyl, propionyloxymethyl, butyryloxymethyl, valeryloxymethyl, 1-acetoxyethyl, 2-acetoxyethyl, 1-pivaloyloxyethyl and 2-pivaloyloxyethyl; a higher alkanoyloxy lower alkyl group such as palmitoyloxyethyl, heptadecanoyloxymethyl and 1-palmitoyloxyethyl; a lower alkoxycarbonyloxy lower alkyl group such as methoxycarbonyloxymethyl, 1-butoxycarbonyloxyethyl and 1-(isopropoxycarbonyloxy)ethyl; a carboxy lower alkyl group such as carboxymethyl and 2-carboxyethyl; a heteroaryl group such as 3-phthalidyl; an optionally substituted benzoyloxy lower alkyl group such as 4-glycyloxybenzoyloxymethyl; a (substituted dioxolene) lower alkyl group such as (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl; a cycloalkyl-substituted lower alkanoyloxy lower alkyl group such as 1-cyclohexylacetyloxyethyl; a cycloalkyloxycarbonyloxy lower alkyl group such as 1-cyclohexyloxycarbonyloxyethyl; etc. That may be also in various acid amides. In short, any group may be a protective group for the carboxyl group so far as it is decomposed in vivo by certain means to give a carboxylic acid.
The term xe2x80x9ca ring which is formed together with the nitrogen atom to which they are bondedxe2x80x9d in the definitions for R7, R8, R21 and R22 represents aziridine, azetidine, pyrrolidine, piperidine, perhydroazepine, perhydroazocine, piperazine, homopiperazine, morpholine, thiomorpholine, etc. Such a ring may be substituted with a lower alkyl group, a halogen atom or acyl group, etc.
It goes without saying that, in the case of a compound having an asymmetric atom in the present invention, an optically active substance thereof is also covered by the present invention. The present invention further covers a hydrate.
Examples of a pharmacologically acceptable salt in the present invention are an inorganic salt such as hydrochloride, hydrobromide, sulfate and phosphate; an organic acid salt such as acetate, maleate, tartrate, methanesulfonate, benzenesulfonate and toluenesulfonate; and a salt with amino acid such as aspartic acid and glutamic acid.
A group of the compounds of the present invention is useful also from the viewpoint of low toxicity and high safety.
When the compound of the present invention is used for the above-mentioned diseases, it may be administered either orally or parenterally. It may be administered in a form of a pharmaceutical preparation such as tablets, powder, granules, capsules, syrup, troche, inhalant, suppository, injection, ointment, ophthalmic ointment, eye drops, nose drops, ear drops, poultice and lotion.
The dose significantly varies depending upon type of the disease, degree of the symptom, age, sex and sensitivity of the patient, etc. but, usually, administration is carried out in a dose of about 0.03-1000 mg, preferably 0.1-500 mg, and more preferably 0.1-100 mg per day to an adult either once daily or dividing into several times a day. In the case of an injection preparation, the dose is usually about 1 xcexcg/kg to 3000 xcexcg/kg, preferably about 3 xcexcg/kg to 1000 xcexcg/kg.
In the manufacture of a pharmaceutical preparation of the compound of the present invention, that is carried out by a conventional means using a common pharmaceutical carrier.
Thus, in the manufacture of a solid preparation for oral use, after addition of filler, binder, disintegrating agent, lubricant, coloring agent, corrective agents for taste and smell, antioxidant, etc. to the main ingredient, then the mixture is made into tablets, coated tablets, granules, powder, capsules, etc. by a conventional manners.
With regard to the above filler, its examples which may be used are lactose, corn starch, sucrose, glucose, sorbitol, crystalline cellulose, silicon dioxide, etc.
With regard to the binder, polyvinyl alcohol, polyvinyl ether, ethyl cellulose, methyl cellulose, gum arabic, tragacanth, gelatin, shellac, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, calcium citrate, dextrin, pectin, etc. may be used for example while, with regard to the lubricant, magnesium stearate, talc, polyethylene glycol, silica, hydrogenated vegetable oil, etc. may be used for example.
With regard to the coloring agent, anything may be used so far as it is permitted to add to pharmaceuticals. With regard to the corrective agents for taste and smell, cocoa powder, menthol, aromatic acid, peppermint oil, borneol, cinnamon powder, etc. may be used. With regard to the antioxidant, anything may be used so far as it is permitted to add to pharmaceuticals such as ascorbic acid and xcex1-tocopherol. It is of course possible that tablets and granules are appropriately coated with sugar, gelatin and others as required.
On the other hand, in the manufacture of injection, eye drops, etc., it is possible to manufacture by a conventional means by adding, if necessary, pH adjusting agent, buffer, suspending agent, auxiliary solubilizer, stabilizer, isotonizing agent, antioxidant, preservative, etc. to the main ingredient. In that case, it is also possible to prepare a freeze-dried preparation, if necessary. The injection may be administered intravenously, subcutaneously or intramuscularly.
Examples of the above-mentioned suspending agent are methyl cellulose, polysorbate 80, hydroxyethyl cellulose, gum arabic, tragacanth, carboxymethyl cellulose sodium and polyoxyethylene sorbitan monolaurate.
Examples of the auxiliary solubilizer are polyoxyethylene hydrogenated castor oil, polysorbate 80, nicotinamide and polyoxyethylene sorbitan monolaurate.
With regard to the stabilizer, sodium sulfite, sodium metasulfite, ether, etc. may be used for example while, with regard to the preservative, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, sorbic acid, phenol, cresol, chlorocresol, etc. may be used for example.
In the manufacture of the ointment, it can be manufactured by a conventional means by addition of stabilizer, antioxidant, preservative, etc. if necessary.
The novel purine compound of the present invention may be manufactured by combining the commonly known methods. As hereunder, main common manufacturing methods for a group of the compounds of the present invention will be given.

In the above formulae, L1 and L2 represent halogen atom; R2xe2x80x2 represents xe2x80x94NR7R8 (wherein xe2x80x94NR7R8 has the meaning as defined above); R9 represents a lower alkyl group; and R1, R3 and R4 have the meaning as defined above.
Step A1
This is a step where 4,6-dihalo-5-nitro-2-pyrimidinylacetamide 1 which is a compound synthesized according to a known method is reacted with an amine compound in a solvent whereupon only one halogen is substituted with an amine compound to manufacture 4-aminopyrimidine compound 2.
There is no particular limitation for the solvent used therefor so far as it does not disturb the reaction and is able to dissolve the starting substance to some extent and its preferred examples are ether such as tetrahydrofuran, dioxane, dimethoxyethane and diethylene glycol dimethyl ether; and a halogenated hydrocarbon such as methylene chloride, chloroform and dichloroethane. The reaction temperature varies depending upon the reactivity of the amine compound used and is preferably xe2x88x9220xc2x0 C. to 50xc2x0 C., and more preferably, about 0xc2x0 C.
In this step, it is preferred to add an equimolar amount of acetic acid to suppress the production of a di-substituted substance.
Step A2
This is a step where a nitro group of the nitropyrimidine compound 2 is reduced by means of a catalytic reduction, a reduction with metal and metal salt, or a metal hydride to manufacture a pyrimidinylamine compound 3.
The catalytic reduction is carried out in a hydrogen atmosphere in the presence of a catalyst such as Raney Ni, Pdxe2x80x94C or PtO2 under ordinary pressure or high pressure at room temperature or with warming. There is no particular limitation for the solvent used so far as it does not act as a catalyst poison and is able to dissolve the starting material to some extent and its suitable examples are methanol, ethanol, tetrahydrofuran, dioxane, acetic acid, dimethylformamide and a mixture thereof. Reduction with metal and metal salt is carried out using zinc dust-hydrochloric acid, stannous chloride-hydrochloride acid, iron-hydrochloric acid, etc. in a solvent of an alcohol such as anhydrous methanol or ethanol or dioxane and tetrahydrofuran. Reduction using a metal hydride is carried out in a solvent of methanol, ethanol or tetrahydrofuran using Pd-sodium borohydride, NiCl2(PPh3)2xe2x80x94 sodium borohydride, stannous chloride-sodium borohydride, etc.
Step A3
This is a step where an amino group and an aldehyde which are adjacent on a pyrimidine ring is condensed with an imidazole ring to manufacture a purine compound 4.
The reaction is carried out in such a manner that an amino group is condensed with an aldehyde compound to give Schiff base, and then it is treated with ferric chloride, etc. to result in a ring closure.
There is no particular limitation for the solvent used so far as it does not disturb the reaction and is able to dissolve the starting material to some extent and its preferred examples are alcohol such as methanol and ethanol; ether such as tetrahydrofuran, dioxane, dimethoxyethane and diethylene glycol dimethyl ether; and dimethylformamide. The reaction is carried out at 0 to 100xc2x0 C., and preferably, at room temperature. It is preferred to add acetic acid during the manufacture of Schiff base.
Step A4
This is a step where an acyl group which is a protecting group of the amino group at position 2 of the above purine compound A is eliminated to manufacture a 2-aminopurine compound 5.
The reaction is carried out by means of a treatment with a mineral acid or an alkaline aqueous solution in a solvent such as methanol, ethanol, dioxane and tetrahydrofuran. Although the reaction proceeds even at room temperature, it is preferred to carry it out with heating.
This step may be completed in the above step A3 depending upon the reducing condition, and in that case, this step is omitted.
Step A5
This is a step where an amino group of the 2-aminopurine compound 5 is subjected to a Sandmeyer reaction to convert into a halogen atom to manufacture a 2,6-dihalopurine compound 6.
The reaction is carried out in such a manner that the amino group is diazotized with sodium nitrile or ester nitrous such as amyl nitrite and isoamyl nitrite to give a diazonium group and then the diazonium group is converted to a halogen atom using cuprous halide. When a nitrite such as isoamyl nitrite is used in the diazotization, an acid is not particularly necessary but the amino group can be converted to a halogen atom by addition of cuprous halide and methylene halide in a solvent such as dioxane or tetrahydrofuran followed by heating. In the present invention, it is most preferred that cuprous iodide is used as a cuprous halide and diiodomethane is used as a methylene halide to convert into a 2-iodopurine compound.
Step A6
This is a step where a halogen atom at position 2 of the 2,6-dihalopurine compound f is selectively subjected to a coupling reaction with an ethynyl side chain to manufacture a 2-ethynylene-6-halopurine compound 7.
The reaction is carried out at room temperature or with heating in the presence of catalytic amounts of dichlorobistriphenylphosphine palladium (II) and cuprous iodide and a tertiary amine. Examples of the solvent used are ether such as tetrahydrofuran, dioxane, dimethoxyethane and diethylene glycol dimethyl ether; dimethylformamide; and 1-methylpyrrolidinone. Examples of the tertiary amine used are triethylamine, diisopropylethylamine, DBU and dimethylaniline. The reaction temperature is preferably 0 to 100xc2x0 C., and more preferably, room temperature.
Step A7
This is a step where a halogen atom of the 2-ethynylene-6-halopurine compound 7 is reacted with an amine compound to manufacture a 6-amino-2-ethynylenepurine compound 8.
When the amine compound is gaseous or has a low boiling point, it is preferred that the reaction is carried out in a sealed tube or in an autoclave.
There is no particular limitation for the solvent used so far as it does not disturb the reaction and is able to dissolve the starting material to some extent and its preferred examples are alcohol such as methanol and ethanol; ether such as tetrahydrofuran, dioxane, dimethoxyethane and diethylene glycol dimethyl ether; halogenated hydrocarbon such as methylene chloride, chloroform and dichloroethane; dimethylformamide; and 1-methylpyrrolidinone.
The reaction temperature is preferably 0 to 150xc2x0 C., and more preferably, 50 to 100xc2x0 C.

In the above formulae, L1, R1, R2xe2x80x2, R4 and R9 have the meanings as defined above.
This manufacturing method B is another method for the manufacture of the 2-acylamino-6-halo-5-nitro-4-pyrimidinylamine compound 3 in the manufacturing method A.
Step B1
This is a step where 2-acylamino-4-chloro-5-nitro-6-pyrimidone compound 1 manufactured by a known method is reacted with an amine compound to manufacture 2-acyl-amino-4-(substituted amino)-5-nitro-6-pyrimidone compound 2.
There is no particular limitation for a solvent used so far as it does not disturb the reaction and is able to dissolve the starting material to some extent and its preferred examples are ether such as tetrahydrofuran, dioxane, dimethoxyethane and diethylene glycol dimethyl ether; and halogenated hydrocarbon such as methylene chloride, chloroform and dichloroethane. The reaction temperature varies depending upon the reactivity of the amine compound used and it is preferably xe2x88x9220xc2x0 C. to 50xc2x0 C., and more preferably, about 0xc2x0 C.
Step B2
This is a step where an oxo group of the pyrimidone compound is converted into a halogen atom to manufacture 2-acylamino-6-halo-5-nitro-4-pyrimidinylamine compound 3.
The reaction is carried out in the absence of solvent or by suspending in a solvent such as acetonitrile, dioxane or tetrahydrofuran and by treating with a halogenating agent such as phosphorus oxychloride or phosphorus oxybromide with heating under reflux. The reaction is accelerated when tetraethylammonium chloride or dimethylformaide is added to the reaction system.

In the above formulae, L1, L2, R1, R2xe2x80x2, R3 and R4 have the meanings as defined above.
This manufacturing method C is that where L1 at position 6 on a purine ring of the 2,6-dihalopurine compound 6 in the manufacturing method A is firstly aminated and then L2 at position 2 is converted to an ethynylene group to manufacture the aimed compound.
Step C1
This is a step where a halogen atom at position 6 of the 2,6-dihalopurine compound 1 is reacted with an amine compound to manufacture a 6-amino-2-halopurine compound 2.
When the amine compound is gaseous or has a low boiling point, it is referred that the reaction is carried out in an autoclave.
There is no particular limitation for the solvent used so far as it does not disturb the reaction and is able to dissolve the starting material to some extent and its preferred examples are alcohol such as methanol and ethanol; ether such as tetrahydrofuran, dioxane, dimethoxyethane and diethylene glycol dimethyl ether; halogenated hydrocarbon such as methylene chloride, chloroform and dichloroethane; dimethylformamide; and 1-methylpyrrolidinone.
The reaction temperature is preferably 0 to 150xc2x0 C., and more preferably, 50 to 100xc2x0 C.
Step C2
This is a step where the aimed compound is prepared by the same operation as in the above-mentioned step A6.
The reaction is carried out at room temperature or with heating in the presence of catalytic amounts of dichlorobistriphenylphosphine palladium (II) and cuprous iodide and a tertiary amine. Examples of the solvent used are ether such as tetrahydrofuran, dioxane, dimethoxyethane and diethylene glycol dimethyl ether; dimethylformamide; and 1-methylpyrrolidinone. Examples of the tertiary amine used are triethylamine, diisopropylethylamine, DBU and dimethylaniline. The reaction temperature is preferably 0 to 100xc2x0 C. and, more preferably, room temperature.

In the above formulae, Q is an alkylene group, an optionally substituted arylene group; an optionally substituted heteroarylene group; an optionally substituted alkylenearylene group; an optionally substituted alkyleneheteroarylene group; an optionally substituted arylenealkylene group; or an optionally substituted heteroarylenealkylene group and R1, R2 and R3 have the meanings as defined above.
This manufacturing method D is a method where, in the case the compound 1 manufactured by the manufacturing method A or C has a cyano group, the cyano group is converted whereupon an amide compound, an amidine compound or an N-cyanoamidine compound is manufactured. Accordingly, when a cyano group is present on the substituents of R2 and R3, the above compounds can be manufactured in a similar manner.
Step D1
This is a step where an amide compound is manufactured from the cyano compound 1 manufactured by the manufacturing method A or C.
The reaction is carried out by treating with an aqueous solution of sodium hydroxide or potassium hydroxide in the presence of a peracid in a water-miscible solvent such as acetone, dioxane, tetrahydrofuran, methanol and ethanol. The reaction temperature is preferably from 0xc2x0 C. to a refluxing temperature and, more preferably, room temperature.
Step D2
This is a step where an amidine compound is manufactured from the cyano compound 1 manufactured by the manufacturing method A or C.
It is possible to manufacture by various methods. For example, a mono-substituted substance may be manufactured by a method where a cyano compound 1 is heated to 200xc2x0 C. or higher with an equimolar aromatic amine benzenesulfonate or p-toluenesulfonate; an N,N-disubstituted substance may be manufactured by a method where an amine compound is heated with a cyano compound 1 in the presence of a Lewis acid such as aluminum chloride; and an unsubstituted substance may be manufactured by a method where a cyano compound 1 is treated with an aluminum amide reagent (MeAlClNH2) or by a method where it is converted into an imidate hydrochloride with hydrogen chloride-ethanol followed by treating with ammonia. Alternatively, the mono- or di-substituted substance may be manufactured by treating the imidate hydrochloride with a primary or secondary amine.
Step D3
This is a step where an N2-cyanoamidine compound is manufactured from the cyano compound 1 manufactured by the manufacturing method A or C.
A cyano compound 1 is dissolved in dioxane or tetrahydrofuran, hydrogen sulfide is passed thereinto to saturate, the mixture is allowed to stand at room temperature to convert into thioamide, and then the thioamide is treated with iodomethane to give thioimidate. The thioimidate is treated with cyanamide whereupon an N-cyanoamidine compound 4 is manufactured. When this operation is applied to a 2-iodo-6-purinylamine compound manufactured in the step C1 of the manufacturing method C and the firstly prepared 2-iodo-N-cyanoamidine compound is coupled with an alkyne reagent, a cyano compound 1 is manufactured in a similar manner.

(in the formula, R12 represents a protective group for a carboxyl group; R13 and R14 are the same as or different from each other and each represents hydrogen atom, an optionally substituted lower alkyl group, an optionally substituted aryl group or an optionally substituted heteroaryl group; and R1, R2xe2x80x2 and R3 have the meanings as defined above.)
Step E1
This is a step where the protective group is eliminated by an acid or an alkali or by means of heating to manufacture a carboxylic acid compound 2.
Examples of the acid used are an aqueous solution of mineral acid such as hydrochloric acid and sulfuric acid while examples of an alkali are an aqueous solution of sodium hydroxide, potassium hydroxide and lithium hydroxide. With regard to a solvent, any solvent may be used so far as it does not participate in the reaction and that which is miscible with water such as methanol, ethanol, tetrahydrofuran and dioxane is preferred. Preferred reaction temperature is from room temperature to refluxing temperature.
When the protective group is a tetrahydropyranyl group, it can be eliminated by heating at from 70 to 150xc2x0 C.
Step E2
This is a step where the carboxylic acid compound 2 previously prepared is converted into a reactive derivative of the acid and made to react with a primary or secondary amine to manufacture an acid amide compound 3.
Examples of the reactive derivative of the acid are an acid halide such as acid chloride; a mixed acid anhydride such as ethoxycarbonyl chloride obtained by the reaction with chloroformate; and an activated ester such as p-nitrophenyl ester. Examples of the solvent are tetrahydrofuran, dioxane, dichloromethane, chloroform and dichloroethane. The reaction temperature is preferably from xe2x88x9210 to 50xc2x0 C., and more preferably, from 0xc2x0 C. to room temperature.
Step E3
This is a step where the ester compound 1 is reacted with an amine compound to directly manufacture an acid amide compound 3 without by way of a carboxylic acid compound 2.
With regard to a protective group R12, a lower alkyl group such as a methyl group or an ethyl group is preferred. The reaction is carried out by heating in a sealed tube or in an autoclave. The reaction temperature is preferably from 50 to 100xc2x0 C.
The above eliminating reaction and amidation reaction can be used for the case where R1 or R3 has a protected carboxyl group as well to manufacture a product.

(in the formulae, n represents an integer of from 2 to 6 and R2xe2x80x2, R3, R12, R13 and R14 have the meanings as defined above.)
Step F1
This is a step where a purine compound 1 having a hydroxyl-substituted alkyl group is oxidized to manufacture a carboxylic acid compound 2.
With regard to an oxidizing agent, ruthenium tetraoxide, permanganic acid, chromic acid, etc. may be used. With regard to a solvent, carbon tetrachloride, chloroform, methylene chloride, acetonitrile, pyridine, water or a mixed solvent thereof may be used. The reaction is carried out preferably at 0 to 50xc2x0 C., and more preferably, at room temperature.
A carboxylic group of the carboxylic acid compound 2 manufactured as such is then protected and, after that, conversion into a 2-ethynylenepurine compound is carried out by the same operation as in the step A6 of the manufacturing method A.
When there is a hydroxyl-substituted alkyl group is present in R3, the same method is applied whereupon a 2-ethynylenepurine compound having a carboxyl group in R3 is manufactured by the same method.

(in the formulae, R2xe2x80x3 is an amino group or a halogen atom; and R1, R3 and R4 have the meanings as defined above.)
Step G1
This is a step where the amino group or the halogen atom at position 6 of the purine skeleton is hydrolyzed to manufacture a 6-hydroxypurine compound 2.
The hydrolysis is carried out in the presence of an acid or an alkali and it is preferred to carry out in the presence of an alkali. Examples of the alkali used are sodium hydroxide, potassium hydroxide, etc. The reaction is carried out at from 0 to 100xc2x0 C.
Step G2
This is a step where the amino group at position 6 is diazotized and heated to eliminate the nitrogen whereupon a 6-unsubstituted purine compound is manufactured.
The reaction is carried out in such a manner that the amino group is diazotized with sodium nitrite or nitrous ester such as amyl nitrite, isoamyl nitrite, etc. in dioxane, tetrahydrofuran or an aqueous solvent thereof and then the diazonium group is eliminated by heating under refluxing.
Incidentally, a method for the manufacture of the compound represented by the formula (VII) is described in JP-A 6-16559 and JP-A 6-211856, J. Med. Chem., 36, 1333-1342, 1993. etc.; a method for the manufacture of the compound represented by the formula (VIII) is described in JP-A 5-97855 and WO 94/14812; a method for the manufacture of the compound represented by the formula (IX) is described in WO 95/01356 and Eur. J. Med. Chem., 28, 569-576, 1993.; and a method for the manufacture of the compound represented by the formula (X) is described in WO 98/42711.
Now, in order to explain the excellent effect of the purine compounds of the present invention, pharmacological experiments will be shown as hereunder.
Effect of Novel Purine Compounds
Hepatic cells were separated by a collagenase perfusion method from liver of male rats of Wistar strain and subjected to a primary culture in a William""s Medium E containing 5% of calf serum, 10xe2x88x926 M of insulin, 10xe2x88x927 M of dexamethasone and 30 ng/ml of pertussal toxin. After one day, the hepatic cells were washed with a Krebs-Ringer Bicarbonate buffer (pH 7.4 (KRB)) containing 10 mM of HEPES and 0.1% of bovine serum albumin and incubated with KRB at 37xc2x0 C. After 30 minutes, 0.1 xcexcM of NECA (N-ethylcarboxamide adenosine) and a test compound were added thereto at the same time, the mixture was incubated for additional one hour and the amount of glucose released into an incubation medium was measured.
The result is shown in Table 1.
Animals: Five male KK-Ay/Ta Jcl mice for each group (purchased from Nippon Clair)
Preparation and Administration of Test Compound: A test compound in a dose as shown in Table 2 was suspended in a 0.5% aqueous solution of methyl cellulose and was orally administered in a dose of 10 ml/kg.
Collection of Blood Samples and Determination of Blood Sugar: Blood was collected from tail vein immediately before administration of the test compound and also five hours after the administration and blood sugar was determined.
Method: Tail vein of a mouse was injured by a razor without an anesthetization to bleed slightly. The blood (15 xcexcl) was collected and immediately mixed with 135 xcexcl of a 0.6 M perchloric acid. Glucose in the supernatant obtained by a centrifugal separation (at 1500 g for 10 minutes at 4xc2x0 C. using a cooling centrifuge GS-6KR of Beckmann) was determined by a Glucose CII Test Wako (Wako Pure Chemicals).
The result for each experiment is shown in Tables 2-1 to 2-3.
The result is shown in terms of xe2x80x9c(% ratio of the blood sugar after 5 hours from the administration to the blood sugar before the administration)xc2x1(standard error)xe2x80x9d. The data were subjected to a one-way layout analysis of variance and then subjected to a multiple comparison of a Dunnett type. The case where p less than 0.05 was judged to be that a significant difference was available.
As such, the compounds of the present invention showed a clear effect to the pathological models. In addition, the compounds of the present invention showed an improving action in the investigation for impaired glucose tolerance in a glucose tolerance test and were confirmed to act not only in liver but also in periphery.
Now, representative compounds of the novel purine compounds according to the present invention will be illustrated and it goes without saying that the object is to facilitate the understanding of the present invention and that the present invention is not limited thereby.